A variety of conjugated compounds have been developed as organic n-type semiconductors, for use as materials in organic thin film devices such as organic transistors, organic solar cells and optical sensors. Specific examples include compounds with fluoroalkyl groups introduced into oligothiophenes (Patent documents 1-4).
Thin films containing organic materials with electron transport or hole transport properties have potential applications in organic thin-film devices including organic thin-film transistors, organic solar cells, optical sensors and the like, and because organic n-type semiconductors (that exhibit electron transport properties) are harder to obtain than organic p-type semiconductors (that exhibit hole transport properties), a great deal of research is being centered on developing organic n-type semiconductors.
In recent years, much research has been conducted on compounds having thiophene rings, fluoroalkyl groups introduced into which, with increased electron acceptability of π-conjugated compounds, as electron transport materials for organic n-type semiconductors and the like (Patent document 1).
On the other hand, several polythiophenes having crosslinked structures are also being studied in order to improve planarity in the molecular structure (Patent document 5).    [Patent document 1] U.S. Patent Application Publication No. 2004/186266    [Patent document 2] U.S. Patent Application Publication No. 2004/183068    [Patent document 3] International Patent Publication No. WO2003/010778    [Patent document 4] European Patent Application Publication No. 1279689    [Patent document 5] Japanese Unexamined Patent Application Publication No. 2004-339516